In a core network of a mobile communication system, the entirety of nodes in the core network need to have necessary functions for each service in order to provide various services to various terminals (mobile terminals). For example, in a large-scale mobile communication network, many nodes are disposed in a core network. Terminals are connected to nodes in the core network, in a distributed manner, on per a location registration.
Thus, the entirety of nodes in the core network need to have necessary functions (service provision functions) for each service. If one of the nodes in the core network should not have necessary service provision functions, service continuity could not be ensured.
PTL 1 discloses a configuration for optimizing a packet forwarding path(s) based on a type of a service used by a mobile station. According to PTL 1, when the mobile station uses a service provided by an external network, a constraint is given to a packet forwarding path(s) so that packets flow through a specific packet forwarding apparatus(es) based on the external network. When the mobile station uses a service provided by a mobile communication network, no constraint is given to a packet forwarding path(s).    PTL 1: Japanese Patent Kokai Publication No. 2003-338832A